Of the traditional methods for collecting marketing data using information technology, information collection based on sales data acquired using a point of sales (POS) system is known and being used actively. Further, there has been in recent years a growing interest in using, as marketing data, data which does not manifest itself in the form of sales data but represents the degree of interest in a commodity, for example, data indicating that a purchaser has picked up a commodity but returned it (such data will be referred to as “purchase sign data”).
Known examples of the method of acquiring purchase sign data, such as data indicating that a purchaser has picked up but returned it, include a method of attaching RF tags to commodities and using a phenomenon in which when a purchaser picks up any commodity, the tag information of a corresponding RF tag is read. However, such an RFID system use method has the following problems.
A first problem is that the tag information of a RF tag may be read illegally. For example, if an RFID system is used to manage commodities on a showcase at a retail store, a third party other than a consumer (customer) who is about to purchase one commodity or a store clerk who is involved in the management of the commodities can read the tag information of an RF tag attached to the commodity. The third party can, for example, associate the commodity which the customer is about to purchase or has purchased, with the customer, resulting in a privacy violation problem. Further, managing raw materials or products for shipment stored in a warehouse by using an RFID system in a similar manner involves an information security problem that a third party can read the tag information of any RF tag to know the storage/shipment state of a corresponding raw material or product.
A second problem is that an RF tag is costly. While the per-unit cost of UHF-band tags is currently being reduced to levels less than 10 yen, this cost is higher by about double digits than, for example, barcodes, which are also being used to manage articles, particularly, commodities. For this reason, it is difficult to attach an RF tag to an article whose cost is approximately 1000 yen or less, in terms of cost.
Patent Literature 1 discloses a technology for coping with these problems. As with the above RFID system use method, the technology of Patent Literature 1 aims to manage articles. More specifically, Patent Literature 1 relates to a smart shelf using an RFID system, more specifically, to a technology for monitoring the presence or absence of articles on a shelf.
In Patent Literature 1, multiple RF tags are disposed on a shelf, and managed (hereinafter referred to as “target articles”) are placed in such a manner that the target articles hinder an RFID reader from reading the RF tags disposed on the shelf. Specifically, in Patent Literature 1, the target articles are placed between the RF tags and an antenna included in the RFID reader. In Patent Literature 1, the number of articles is monitored according to the following procedure.
(a) The RFID reader emits electromagnetic waves toward the shelf.
(b) The RFID reader determines the number of RF tags whose tag information it cannot read due to the presence of articles corresponding to the RF tags.
(c) The RFID reader determines the number of articles on the basis of the information obtained in (b).
Note that when the articles are placed between the reader and tags, the RF tags are adjusted so that the articles hinder the reader from reading the tags.
According to the technology of Patent Literature 1, when one target articles are placed between the RFID reader and the RF tags, that is, when the target articles are present on the shelf, the articles block the RF tags and the RFID reader from being viewed, thereby preventing the RFID reader from reading the tag information of the RF tags. Specifically, when there is one target article, the tag information of the RF tag corresponding to the article cannot be read, so that the presence of the target article can be detected. On the other hand, there is no management target article on the shelf, specifically, when there is no target article between the RFID reader and the RF tags, there is no target article that blocks the views of the RF tags and the RFID reader, so that the RFID reader can read the tag information of the RF tag. Thus, when there is no target article, the tag information corresponding to the article can be read, so that the absence of the article can be detected. As a result, in Patent Literature 1, the presence or absence of articles can be detected and thus the articles on the shelf can be managed. Note that articles to be managed are required to contain a metal, water, or the like, which hinders transmission of energy with a radio frequency.
According to the technology of Patent Literature 1, the RF tags are not attached to the target articles but rather left on the shelf. Thus, a third party is prevented from illegally reading the tag information of an RF tag attached to any target article, thereby preventing privacy violation or information security problem. This is, the technology of Patent Literature 1 prevents illegal reading of the tag information of any RF tag by a third party, which is the first problem. Further, the technology of Patent Literature 1 allows the RF tags to be used repeatedly, since the RF tags are not attached but left on the shelf. Thus, the per-article tag cost substantially becomes a value obtained by dividing the tag cost by the number of times the tag is used. That is, according to the technology of Patent Literature 1, the problem that an RF tag is costly, which is the second problem, is solved by using the tag a sufficient number of times.